The invention is based on a process for producing an angled bore in a component. A process of this kind for producing an angled bore has been disclosed by the reference DE-OS 195 47 423 for producing the fuel supply conduit in a valve holding body of a fuel injection valve for internal combustion engine. The supply conduit in the valve body, which conduit is embodied there as an angled bore, is embodied by way of an oblique bore from a first end face of the valve holding body, which bore feeds into a longitudinal bore in the valve holding body that is eccentrically let in from the second end face. Thus, a sharp and indefinite intersection is produced at the transition between the two bores, wherein fatigue fractures are produced at this intersecting edge when there are high compression threshold loads of the fuel flowing through the inside of the supply conduit, particularly those above 1800 bar. Even modern manufacturing processes for grinding this bore transition between the oblique bore and the straight bore, e.g. with an abrasive grinding means, are insufficient to increase the compression threshold strength in this bore transition region so that it also suffices for very high loads of the kind that occur, for example, in modern internal combustion engines.
Furthermore, this kind of angled bores can currently be produced only at a high manufacturing cost.
The process according to the invention for producing an angled bore in a component has the advantage over the prior art that an angled bore can be produced inside a body in a manner that is simple for technical manufacturing reasons, wherein the transition between the oblique bore part and the straight bore part is embodied without an intersecting edge. On the one hand, this has the advantage that the flow behavior inside the angled bore can be improved and that in addition, the high-pressure tightness and thereby in particular the compression threshold strength at the transition between the oblique bore and the straight bore can be sharply increased in relation to the known manufacturing process. The manufacture of the angled bore thereby occurs in a simple manner by means of two essential process steps: in a first step, the bore is let into a component as a straight bore and in a second step, this component is deformed so that an angled bore course is produced. In this connection, the component, e.g. in its initial state before the production of the bore, can have an angled shape and after the boring process, is brought into a straight shape so that an angled bore is produced in a straight component.
Alternatively, this process can also be used in a component that is straight in its original state, e.g. a cylindrical component, wherein three main process steps are now required. In this connection, in a first main process step, the component is deformed out of its original shape, for example is bent. In another, second main process step, the bore, preferably a through bore, is let into the component wherein starting from a first end face, this bore can now be advantageously embodied as a bore that passes straight through axially. In a third main process step, the part of the component which was bent out of the original shape in the first process step is deformed back into the original shape, preferably bent back, so that the component now once more has essentially the same shape as it did before the production of the bore. This deformation is preferably produced by means of a bending process, wherein if need be, the component is thermally heated before the deformation. Slight shape deviations before and after the manufacturing process of the bore in the component can occur depending on the manufacture, but are so small that they remain within certain tolerances and are consequently negligible. The angled bore can thereby extend from one end face of the component to the opposite one, but it is alternatively also possible to provide the entry or exit opening of the bore on the radial circumference wall.
The manufacturing process of angled bores according to the invention is suitable for all components which preferably have an elongated shape, e.g. cylinders. The manufacturing process for angled bores according to the invention can be used in all areas of mechanical engineering, in particular fuel injection technology for internal combustion engines, and is described in the following exemplary embodiment of a valve holding body of a fuel injection valve for internal combustion engines in which very high loads occur in terms of the compression threshold strength. The angled bore in the exemplary embodiment is embodied as a through bore from a first end face to a second end face of the component, but alternatively, angled blind bores can also be produced by means of the manufacturing process according to the invention. Furthermore, the angled bore can be embodied as a diametrically uniform bore, but it is also possible to embody it as a stepped bore with different bore diameters, as described in the exemplary embodiment. To this end, after the production of the first bore with the smaller bore diameter, a second bore with a correspondingly larger bore diameter is advantageously produced, wherein the bore depth then determines the length of the larger diameter bore.
Other advantages and advantageous embodiments of the subject of the invention can be inferred from the description, the drawings, and the claims.